Fishermen and marine engineers use a variety of devices to enhance their observations of subsurface phenomena. Fishermen often use polarizing sunglasses to eliminate surface reflections and thus enhance their ability to see subsurface objects. “Inverted” periscope devices (i.e., periscope devices which enable an observer above the water surface to view objects beneath the water surface, in contrast to conventional submarine periscopes which are designed to allow a submerged observer to see objects above water) are commercially available.
As fishing has become a more and more competitive activity over the years, fishermen have constantly sought to improve their results by using technology to detect the presence of fish and features of the aquatic environment. Thus, the use of sonar and related devices such as fish finders to provide information on subsurface objects, creatures and conditions is well established. However, such sonar-type devices tend to be relatively bulky and require substantial power supplies. Thus, they are not easily adapted for use on the small boats often used by fishermen on inland rivers and lakes. Furthermore, the images which sonar-type devices produce, being based upon acoustical properties of the environment rather than visual ones, are often not easy for inexperienced operators to interpret.
Accordingly, there is a continuing need for more effective devices for observing and detecting fish, other wildlife, objects and features of the environment beneath the surface of a lake, stream, river, estuary, ocean or other body of water. Desirably, such devices should be compact, have sufficiently low power requirements to permit operation by storage battery, and produce images based upon visual properties of the environment so that the images are easy for even inexperienced operators to interpret. It is a primary object of this invention to fulfil this need.
Fish and other underwater creatures are of course sensitive to light and indeed, since such creatures may often live in underwater environments where the light level is much lower than at the surface, fish and other creatures may be more sensitive to certain types of lights than are humans and other terrestrial creatures. Accordingly, it is desirable that devices used for underwater observation not require levels of illumination that are likely to scare away the fish or other creatures being sought, and it is a further object of this invention to provide devices which meet this need.
Yet another object of the invention is to control the spectral illumination of the scene and the sensitivity of the image detector to maximize the visibility of features of interest as displayed to the user.
Yet another object of the invention is to provide means to accommodate large variations of natural illumination of the area under observation and to provide supplementary illumination when required.
Yet another object of the invention is to provide video observation systems in a mechanical package having a streamlined profile in the water, this package being readily manipulable by an observer to provide views over a range of directions.
Yet another object of the invention is to provide video observation systems which can be packaged with means for propelling watercraft to which the video observation systems are to be attached. Preferred devices of the present invention using currently available video technology can readily be incorporated into existing trolling motor products with minimal modifications of such products.
Other objects of the invention will be apparent and will appear hereinafter in the following detailed description when read in connection with the drawings.